Preparation of a Clay Composite Containing Poly(o-toluidine) and Halloysite, and Examining of Its Performance as a Humidity Sensor

Abstract

This study outlines the production of an electrically conductive clay-based composite containing the halloysite as clay mineral and poly(o-toluidine) (POT) as a conductive filler. In the study, conductive POT/halloysite composite was obtained by in situ oxidative polymerization of o-toluidine using ammonium persulphate (APS) as an oxidant between the halloysite layers. By changing the polymerization conditions such as polymerization time, o-toluidine concentration, APS, and the concentration of HCl solution used as the reaction medium, the composite with the highest conductivity (7.5×10-5 S.cm-1) was obtained. Structural and morphological changes and thermal behaviors that occurred after the composite formation was revealed using various characterization techniques such as FTIR, XRD, TGA, and SEM. The usability of the prepared POT/halloysite composite as humidity sensing material was tested in comparison with the pure POT component of the composite at a relative humidity (% RH) varied between 41-94 (%). Accordingly, it was found that the composite exhibited a fairly regular resistance change to varying relative humidity compared to pure POT polymer.

Keywords

• conductive clay composite
• poly(o-toluidine)
• halloysite
• humidity sensing
• iletken kil kompoziti
• poli(o-toluidin)
• halloysit
• nem sensörü